The present invention provides a voice service processing method and a terminal device. The method includes: sending, by a terminal device, a first message to a network device of a first network, where the first message is used to request a circuit switched fallback CSFB voice service; receiving, by the terminal device, a second message sent by the network device of the first network, where the second message is used to instruct the terminal device to perform network redirection; if the second message carries no frequency information, determining, by the terminal device, a redirection frequency, where the redirection frequency is a frequency supported by a second network; and sending, by the terminal device based on the redirection frequency, a connection request to a network device of the second network, to perform a CS voice service.